The utilization of information received during a silent interval between ringing signals, including an incoming call line identification number, is now being incorporated into new private or subscriber-owned communication systems (e.g., key or private branch exchanges (PBX) systems).
One known system is described in U.S. Pat. No. 4,924,496 issued to R. Figa et al. on May 8, 1990. This patent describes an automatic incoming telephone call number display system for detecting an incoming call and identifying the party associated with the incoming call number. The system includes a directory of telephone numbers and parties associated with those numbers. Circuitry detects the origin telephone number of an incoming telephone call and compares that number with numbers in the directory to identify the calling party. A user may access the memory, using control buttons, to select and display a stored telephone call number and party associated with that number. Thereafter, the user may auto-dial the displayed number by pressing a dial button.
In certain situations a user may not want to store all of the received incoming telephone call numbers (as described in the Figa patent) and, thereafter, have to sort through all of the stored incoming telephone call numbers to select the number that he/she would want to dial. For example, when a called party is busy on a call on one line, there exists a need for that party to selectively capture a second incoming telephone call number received on a second line, so that the called party may quickly return the call when he or she is finished with the present call.